Annual Report 2006

Plant Science Division
The Plant Science Division consists of the
following five departments, and is actively
engaged in multidisciplinary researches.
Scientists at the Molecular Genetics
Department are engaged in studies of the
structure and function of plant genomes, genes,
their products, and their networks, which are
involved in various agriculturally important
traits, and also the mechanisms regulating
expression of these genes.
Those at the Biochemistry Department are
involved in researches on the three-dimensional
structure of proteins, and structure-function
relationships of proteins involved in response to
hormones and other biotic signals in plant cells.
Plant Physiology Department is engaged in
analyses of molecular mechanisms of important
physiological processes in plants including
photosynthesis, morphogenesis such as leaf and
floral organ development, the symbiotic process
of nitrogen fixation, mechanisms of defense
against plant pathogens, and tolerance against
environmental stresses.
The Plant Biotechnology Department is
developing new techniques for next-generation
plant biotechnology and also producing novel
transgenic crops with superior traits which
conventional breeding techniques can not
produce.
The Institute of Radiation Breeding is
developing new technologies utilizing radiation
for plant breeding, the creation of plant genetic
resources through mutation induction, and the
elucidation of gene expression mechanisms in
plant mutants.
Major topics in each department are
described the next page.
M
olecular Genetics Department
The research activities of this department
are mainly focused on the analysis of the
structure and function of rice genome, genes
and their products, the development of tools
and resources for functional analysis of rice
genes, and the mechanisms regulating gene
expression. Major topics in the fiscal year 2005
are described as follows.
DNA methylation analysis
DNA methylation is an epigenetic
modification that a methyl group is added to
the 5th carbon of pyrimidine ring of cytosine. It
is informative to systematically scan genomewide
changes of methylation through each
developmental stage, and to precisely analyze
interactions between methylation status and
gene expressions. Restriction landmark genome
scanning (RLGS) is a two-dimensional
electrophoresis of genomic DNA, which
visualizes thousands of loci. We improved RLGS
method to detect methylated sites directly. The
isoschizomers, I andII that recognize
the same sequence (CCGG) but have different
methylation sensitivity were employed. We
detected 22 spots on both RLGS patterns (I
and II) in ecotype
Columbia. In comparison of them, 18% of the
spots were polymorphic, which indicated the
methylation of C 5m CGG sites. And, 52 and 54
restriction enzyme sites were also analyzed in
two other ecotypes, Wassilewskija and
Landsberg erecta, respectively. Consequently,
15% of the 52 common sites showed methylation
polymorphism among the three ecotypes.
Almost all the restriction sites analyzed in this